1. Field of the Invention
The present invention relates to a new type of AC driven self shift gas discharge panel, and to a system and method for driving it, wherein the display screen is divided into several sections both in the horizontal and vertical directions, and the write and shift operations can be made independently in respective ones of the divided display areas, and which allows various improvements in the display function.
2. Description of the Prior Art
As an existing display device utilizing gas discharge, the AC driven type of gas discharge panel is well known. However, since this panel uses matrix addressing, it requires many drivers for operation, and the necessary drivers and related electronic circuitry become very expensive. The self shift type gas discharge panel of the present invention solves such disadvantages of the matrix addressing system.
Basically, a self shift type gas discharge panel has shift channels defined by a regular arrangement of groups of discharge cells, each group being driven by a voltage with a particular phase. Such a panel is driven so that the discharge spots, that are generated when a write voltage is applied to the write discharge cells provided at one end of the shift channels, are sequentially shifted by making use of the coupling effect between adjacent cells. Well known self shift type gas discharge panels of this kind, for example, are (1) those employing a matrix electrode configuration as disclosed in U.S. Pat. No. 3,994,875 by Owaki et al. and assigned to the same assignee as the present invention, (2) those employing a parallel electrode configuration as disclosed in U.S. Pat. No. 3,775,764 by J. P. Gaur, and (3) those employing a meander electrode arrangement or the meander channel configuration as disclosed in U.S. Pat. Nos. 4,185,229 and 4,190,778 of Yoshikawa et al. and also assigned to the same assignee as the present invention.
These self shift panels have the advantage that the number of drivers for the electrodes of the X and Y sides is drastically reduced over that in the matrix address system, since only three or four shift drivers are required. However, such existing self shift type gas discharge panels have the following disadvantages when used for various kinds of monitor and keyboard display with computer terminals. Character information written in character units at one edge of the shift line is shifted horizontally and then is fixed for display at a specified display position. Thus, the panel has a configuration which does not allow random addressing, and therefore the character information to be displayed in one shift line cannot be individually written. Therefore, the aforementioned display panels cannot realize a write operation function in which character information previously written by write command signals sent from a computer is held at a predetermined display position while different information is written into a specified display position of the same shift line, by successive keyboard operation under this holding condition.